Hi just wondering if there does be theme nights or fancy dress on Halloween night in Lisbon.?
Some bars might, but to most Portuguese I know it is a nasty American intrusion upon the much more important All Saints Day, November 1st, which is a public holiday. It's the day when the more traditionally minded visit the family graves to tidy them up and leave flowers.
Tourist and ex pat bars down here in Albufeira do 'Hallowe'en but that's 300km away.
Short answer is, where portuguese live no. In the touristy area with the bars catering for foreigners probably some parties will exist.
Lisbon's taken to Halloween quite well in recent years. There's a whole underground culture of people who take costumes seriously, and every year more and more venues have costume-themed nights - and by far not just in the touristy areas. Most of the people dressed up you'll see on the street - ok, except for that dude in the crappy store-bought Goofy mask - are locals. We take this stuff seriously here. Try this for a start: http://www.atlaslisboa.com/halloween-2017/